Hemoglobin Hakkari: an autosomal dominant form of beta thalassemia with inclusion bodies arising from de novo mutation in exon 2 of beta globin gene

Certain beta globin gene mutations produce a thalassemia major phenotype in the heterozygous state. While most such patients have thalassemia intermedia, we describe a young Guatemalan child with a de novo mutation in the beta globin gene, codon 31 T --> G (Hemoglobin Hakkari), who developed severe anemia at the age of 10 months and remains transfusion-dependent. The substitution of B13 leucine with arginine in the beta globin results in alteration of a critical heme contact point resulting in an extremely unstable variant hemoglobin and a clinical picture that is characterized by ineffective erythropoiesis and numerous intracytoplasmic inclusions within the erythrocyte precursors of the bone marrow. .

Pulmonary hypertension in thalassaemia major patients with normal left ventricular systolic function

Pulmonary hypertension is common in adults with thalassaemia and other haemolytic anaemias. It was hypothesised that regular transfusions in thalassaemia major should both decrease the chronic haemolytic rate and be protective from pulmonary hypertension (PHT). To reduce the contribution of existing cardiac disease to PHT, the subjects were limited to patients with normal left ventricular shortening fractions. Associations with multiple laboratory markers of haemolysis, serum ferritin levels, chest X-rays findings and splenectomy status were also considered. We found no biochemical, transfusional, or clinical (except gender) differences in transfused thalassaemia patients with or without pulmonary hyper tension.

Universal newborn screening for Hb H disease in California

Newborn screening is an accepted public health measure to ensure that appropriate health care is provided in a timely manner to infants with hereditary/metabolic disorders. Alpha-thalassemia is a common hemoglobin (Hb) disorder, and causes Hb H (beta4) disease, and usually fatal homozygous alpha(0)-thalassemia, also known as Hb Bart's (gamma4) hydrops fetalis syndrome. In 1996, the State of California began to investigate the feasibility of universal newborn screening for Hb H disease. Initial screening was done on blood samples obtained by heel pricks from newborns, and stored as dried blood spots on filter paper. Hb Bart's levels were measured as fast-moving Hb by automated high-performance liquid chromatography (HPLC) identical to that currently used in newborn screening for sickle cell disease. Subsequent confirmation of Hb H disease was done by DNA-based diagnostics for alpha-globin genotyping. A criterion of 25% or more Hb Bart's as determined by HPLC detects most, if not all cases of Hb H disease, and few cases of alpha-thalassemia trait. From January, 1998, through June, 2000, 89 newborns were found to have Hb H disease. The overall prevalence for Hb H disease among all newborns in California is approximately 1 per 15,000. Implementation of this program to existing newborn hemoglobinopathy screening in populations with significant proportions of southeast Asians is recommended. The correct diagnosis would allow affected infants to be properly cared for, and would also raise awareness for the prevention of homozygous alpha(0)-thalassemia or Hb Bart's hydrops fetalis syndrome.

Silent infarction as a risk factor for overt stroke in children with sickle cell anemia: a report from the Cooperative Study of Sickle Cell Disease

OBJECTIVE

To determine whether children with homozygous sickle cell anemia (SCD) who have silent infarcts on magnetic resonance imaging (MRI) of the brain are at increased risk for overt stroke.

METHODS

We selected patients with homozygous SCD who (1) enrolled in the Cooperative Study of Sickle Cell Disease (CSSCD) before age 6 months, (2) had at least 1 study-mandated brain MRI at age 6 years or older, and (3) had no overt stroke before a first MRI. MRI results and clinical and laboratory parameters were tested as predictors of stroke.

RESULTS

Among 248 eligible patients, mean age at first MRI was 8.3 +/- 1.9 years, and mean follow-up after baseline MRI was 5.2 +/- 2.2 years. Five (8.1%) of 62 patients with silent infarct had strokes compared with 1 (0.5%) of 186 patients without prior silent infarct; incidence per 100 patient-years of follow-up was increased 14-fold (1.45 per 100 patient-years vs 0.11 per 100 patient-years, P =.006). Of several clinical and laboratory parameters examined, silent infarct was the strongest independent predictor of stroke (hazard ratio = 7.2, P =.027).

CONCLUSIONS

Silent infarct identified at age 6 years or older is associated with increased stroke risk.

Prospective RBC phenotype matching in a stroke-prevention trial in sickle cell anemia: a multicenter transfusion trial

BACKGROUND

Most sickle cell anemia patients undergo transfusion therapy to prevent complications. The Stroke Prevention Trial in Sickle Cell Anemia showed that transfusion therapy is effective in the primary prevention of stroke. Despite its efficacy, transfusion therapy is limited by alloimmunization. The purpose of this study was to determine if a multicenter trial could implement a transfusion program utilizing phenotypically matched blood to reduce alloimmunization.

STUDY DESIGN AND METHODS

One hundred thirty children underwent RBC phenotyping and antibody screening with review of blood bank records. The protocol required use of WBC-reduced RBCs, which were matched for E, C, and Kell. Monthly alloantibody testing and review of transfusion forms were performed to determine compliance and the occurrence of any adverse events.

RESULTS

Patient RBCs expressed a low frequency of Kell (2%), E (20%), and C (25%) antigens. Sixty-one patients received 1830 units. Ninety-seven percent of all units were WBC reduced. Only 29 units were inadvertently not matched for E, C, and Kell. Five patients (8%) developed a clinically significant alloantibody. Four developed a single antibody to E or Kell. Three patients (5%) developed a warm autoantibody. There were 11 transfusion reactions and 8 transfusion-associated events. Transfusion reactions included 6 febrile reactions (0.33%/unit), 3 allergic (0.16%/unit), and 2 hemolytic (0.11%/unit). Associated events included 4 episodes of hypertension (0.22%/unit), 3 crises (0.16%/unit), and 1 transient ischemic attack (0.05%/unit).

CONCLUSION

This is the first multicenter study to show that extended RBC phenotyping can be implemented nationwide. Compared to studies, the alloimmunization rate dropped from 3 percent to 0.5 percent per unit, and hemolytic transfusion reactions dropped by 90 percent. It is recommended that all transfused sickle cell anemia patients be antigen matched for E, C, and Kell. Patients should be closely monitored during transfusions to avoid preventable risks.

Correlation of abnormal intracranial vessel velocity, measured by transcranial Doppler ultrasonography, with abnormal conjunctival vessel velocity, measured by computer-assisted intravital microscopy, in sickle cell disease

The Stroke Prevention Trial has confirmed that utilization of transcranial Doppler ultrasonography (TCD), which examines blood flow in large intracranial vessels, can identify children with sickle cell disease (SCD) who are at high risk of developing a premature stroke. It is not known to what extent the vasculopathy in SCD involves small vessels and whether the abnormalities, if present, correlate with large-vessel vasculopathy. Eighteen children with SCD were examined with TCD to determine middle cerebral artery (MCA) velocity and computer-assisted intravital microscopy (CAIM) to determine bulbar conjunctival vessel velocity during the same visit for vasculopathy correlation. High MCA velocity (≥ 200 cm/sec) was found by TCD in 4 patients who also showed abnormal conjunctival velocity (< 0.2 mm/sec or intermittent trickle flow) by CAIM. Three patients had conditional (≥ 170 cm/sec and < 200 cm/sec) MCA velocity: 2 showed abnormal (trickle) and 1 showed normal conjunctival velocity (1.9 mm/sec). One patient with unmeasurable MCA velocity had abnormal (trickle) conjunctival velocity. Of the remaining 10 patients who had normal MCA velocity, 2 showed abnormal (0.05 mm/sec and 0.1 mm/sec) and 8 showed normal conjunctival velocities (1.1-2.4 mm/sec). The MCA velocities correlated significantly with bulbar conjunctival flow velocities (P ≤ .008, Fisher exact test). A correlation exists between MCA (large-vessel) and conjunctival (small-vessel) flow velocities. CAIM is a noninvasive quantitative technique that might contribute to the identification of SCD patients at high risk of stroke. Small-vessel vasculopathy might be an important pathological indicator and should be further explored in a large-scale study.

Current issues with blood transfusions in sickle cell disease

With increased recognition of the profound morbidity of sickle cell disease and with growing evidence of the efficacy of transfusion therapy in prevention and treatment of sickle cell complications, most patients now receive intermittent transfusion therapy. The purpose of this report is to review blood component therapy and Its risks for sickle cell patients. Packed red cells are the preferred blood component. Leukocyte-reduced units should be standard because of their beneficial effects in reducing alloimmunization, transfusion reactions, platelet refractoriness, and infection transmission. The use of washed, frozen, or Irradiated units is limited to specific problems. Sickle trait-positive units function normally, but because of difficulties with calculating hemoglobin S percentages and leukocyte filters, they are not routinely used. Transfusion-acquired infections have shown a marked decrease but still present a major risk. Viral hepatitis transmission is currently low, but at least 10% of adult sickle cell patients are hepatitis C positive, and they often have liver damage. Although bacterial infections are rare, they account for 16% of transfusion-related fatalities. Patients who are iron overloaded are particularly vulnerable to Yersina enterocolitica. Red cell alloimmunization is a serious problem that could potentially affect 50% of transfused patients. However, preventive phenotypic matching for common antigens can minimize alloimmunization; limited matching for at least E, C, and K has become the standard of care. Recently, more patients are being identified who have developed red cell autoantibodies, which can mask alloantibodies and occasionally are hemolytic. Careful laboratory evaluation of all cases is essential. Transfusions also may trigger sickle cell events, including pain crises, stroke, and acute pulmonary deterioration. In part, these are induced by blood viscosity and increased blood pressure. Diuretic therapy and close monitoring of transfusion volume and vital signs can minimize these events. In summary, transfusion therapy carries risks, but the routine use of leukocyte-reduced, phenotypically matched units in conjunction with close monitoring of patients can make transfusion therapy safer.

Alloimmunization and erythrocyte autoimmunization in transfusion-dependent thalassemia patients of predominantly asian descent

The development of hemolytic alloantibodies and erythrocyte autoantibodies complicates transfusion therapy in thalassemia patients. The frequency, causes, and prevention of this phenomena among 64 transfused thalassemia patients (75% Asian) were evaluated. The effect of red blood cell (RBC) phenotypic differences between donors (mostly white) and Asian recipients on the frequency of alloimmunization was determined. Additional transfusion and patient immune factors were examined. 14 (22%) of 64 patients (75% Asian) became alloimmunized. A mismatched RBC phenotype between the white population, comprising the majority of the donor pool, and that of the Asian recipients, was found for K, c, S, and Fyb antigens, which accounts for 38% of the alloantibodies among Asian patients. Patients who had a splenectomy had a higher rate of alloimmunization than patients who did not have a splenectomy (36% vs 12.8%; P =.06). Erythrocyte autoantibodies, as determined by a positive Coombs test, developed in 25% or 16 of the 64 patients, thereby causing severe hemolytic anemia in 3 of 16 patients. Of these 16, 11 antibodies were typed immunoglobulin G [IgG], and 5 were typed IgM. Autoimmunization was associated with alloimmunization and with the absence of spleen (44% and 56%, respectively). Transfused RBCs had abnormal deformability profiles, more prominent in the patients without a spleen, which possibly stimulated antibody production. Transfusion of phenotypically matched blood for the Rh and Kell (leukodepleted in 92%) systems compared to blood phenotypically matched for the standard ABO-D system (leukodepleted in 60%) proved to be effective in preventing alloimmunization (2.8% vs 33%; P =.0005). Alloimmunization and autoimmunization are common, serious complications in Asian thalassemia patients, who are affected by donor-recipient RBC antigen mismatch and immunological factors.

Secretory phospholipase A(2) predicts impending acute chest syndrome in sickle cell disease

Acute chest syndrome (ACS) is the leading cause of death in sickle cell disease. Severe ACS often develops in the course of a vaso-occlusive crisis (VOC), but currently there are no predictors for its development. Secretory phospholipase A(2) (sPLA(2)), a potent inflammatory mediator, is elevated in ACS, and previous work suggests that sPLA(2) predicts impending ACS. We prospectively evaluated sPLA(2) concentration during 21 admissions for VOC; 6 of these patients went on to develop ACS. Elevation of sPLA(2) was detected all 6 patients 24 to 48 hours before ACS was clinically diagnosed. Adding the requirement for fever raised the specificity of sPLA(2) to 87% while retaining 100% sensitivity. These data indicate that sPLA(2) can be useful in alerting the clinician to patients with impending ACS. In addition, sPLA(2) may be useful for instituting early therapies to prevent or reduce the clinical morbidity of ACS.

Changing outcome of homozygous alpha-thalassemia: cautious optimism

Only a few long-term survivors of homozygous alpha-thalassemia, a usually fatal condition, have been reported. The authors present a surviving infant with this disorder and discuss the complications, treatments, and implications of this genetic hemoglobinopathy. The child had no antenatal intervention and has been treated with regular transfusions. She has had normal growth and development and is currently 2.5-years-old. A literature review of survivors with Bart hemoglobinopathy reveals an intense perinatal course and a great prevalence of congenital urogenital and limb defects. Advances in antenatal diagnosis, intrauterine intervention, and postnatal treatments have resulted in extended survival of children with congenital defects that until recently were considered invariably fatal. Transfusion and chelation therapy and bone marrow transplantation provide long-term treatment and potential curative options.

Patterns of arginine and nitric oxide in patients with sickle cell disease with vaso-occlusive crisis and acute chest syndrome

PURPOSE

Our objective was to evaluate L-arginine and nitric oxide metabolite (NOx) levels in children with sickle cell disease (SCD) at steady-state and during vaso-occlusive crisis (VOC). Because alterations in nitric oxide production may have an important role in the pathophysiology of SCD, our second aim was to determine if a relationship exists between these levels and vaso-occlusive crisis (VOC).

PATIENTS AND METHODS

Plasma L-arginine and serum NOx levels were examined in 36 patients with SCD with 39 episodes of VOC and 10 children with SCD at steady-state. Daily levels were obtained in children requiring hospitalization.

RESULTS

Steady-state L-arginine levels were normal in children with SCD. L-arginine levels were low, however, in children with VOC (37.4 +/- 2.7 vs. 53.6 +/- 4.6 micromol/L; P = 0.008) but returned to baseline during hospitalization. In contrast, NOx levels were normal at presentation but decreased during hospitalization for both patients with VOC and patients with acute chest syndrome (ACS) (21.1 +/- 2.0, 17.4 +/- 2.4, and 12.3 +/- 1.6 micromol/L, respectively; P < 0.05). In the patients with VOC who had ACS develop, L-arginine decreased to the lowest levels at the time of the ACS diagnosis, correlating with decreasing NOx levels.

CONCLUSION

These data suggest that there may be a relationship between the L-arginine-nitric oxide pathway and vaso-occlusion in SCD. Low arginine levels during VOC could reflect a state of acute substrate depletion that results in a decrease in nitric oxide production.

Arginine therapy: a novel strategy to induce nitric oxide production in sickle cell disease

To determine the effects of L-arginine (L-Arg) supplementation on nitric oxide metabolite (NOx) production, oral L-Arg was given to normal controls, sickle cell disease (SCD) patients at steady state and SCD patients hospitalized with a vaso-occlusive crisis (VOC). L-Arg (0.1 g/kg) increased NOx formation by 18.8 +/- 68% in normal controls, whereas steady-state SCD patients demonstrated a paradoxical decrease in NOx of -16.7 +/- 4% (P = 0.004). In contrast, patients with VOC demonstrated a dramatic increase in NOx production by +77.7 +/- 103%, a response that was dose dependent. L-Arg appears to be the rate-limiting step in NOx production during VOC. Oral arginine may therefore benefit SCD patients by inducing an increase in NO production during VOC.

Multicenter comparison of magnetic resonance imaging and transcranial Doppler ultrasonography in the evaluation of the central nervous system in children with sickle cell disease

PURPOSE

To compare the results of standardized magnetic resonance imaging (MRI) of the brain and transcranial Doppler (TCD) ultrasonography of cerebral arteries in school-aged children with sickle cell disease to determine the correlation between these two different neurodiagnostic tests.

PATIENTS AND METHODS

Data were analyzed from 78 children with sickle cell disease (mean age 11 yrs) who participated in both the Cooperative Study of Sickle Cell Disease (CSSCD) and the Stroke Prevention Trial in Sickle Cell Anemia (STOP). Patients who had experienced an overt stroke were excluded. MRI findings were classified as normal or "silent infarct." Results of TCD were classified as normal, conditional, or abnormal, based on the time-averaged maximum mean flow velocity in the proximal middle cerebral and distal internal carotid arteries.

RESULTS

Of 61 patients who had a normal MRI examination, 11 (18%) had either conditional (5 patients) or abnormal (6 patients) TCD results. Among 17 patients in whom silent infarction was seen on MRI, only 5 (29%) had a conditional (1 patient) or abnormal (4 patients) TCD velocity. Thus, discordant results were seen in 23 patients: 12 in which the TCD result was normal and the MRI abnormal; 11 in which the TCD velocity was elevated and the MRI normal.

CONCLUSIONS

Abnormal TCD and MRI examinations reveal different aspects of the pathophysiology of central nervous system (CNS) injury in sickle cell disease and are often discordant. Although TCD abnormality is predictive of overt stroke, the lack of concordance between TCD and MRI findings suggests a need to develop more sensitive and specific indicators of early CNS pathology, such as neuropsychometric testing and positron-emission tomography (PET) scans, and to obtain more information about microvascular pathologic processes that may affect CNS function.

Causes and outcomes of the acute chest syndrome in sickle cell disease. National Acute Chest Syndrome Study Group

BACKGROUND

The acute chest syndrome is the leading cause of death among patients with sickle cell disease. Since its cause is largely unknown, therapy is supportive. Pilot studies with improved diagnostic techniques suggest that infection and fat embolism are underdiagnosed in patients with the syndrome.

METHODS

In a 30-center study, we analyzed 671 episodes of the acute chest syndrome in 538 patients with sickle cell disease to determine the cause, outcome, and response to therapy. We evaluated a treatment protocol that included matched transfusions, bronchodilators, and bronchoscopy. Samples of blood and respiratory tract secretions were sent to central laboratories for antibody testing, culture, DNA testing, and histopathological analyses.

RESULTS

Nearly half the patients were initially admitted for another reason, mainly pain. When the acute chest syndrome was diagnosed, patients had hypoxia, decreasing hemoglobin values, and progressive multilobar pneumonia. The mean length of hospitalization was 10.5 days. Thirteen percent of patients required mechanical ventilation, and 3 percent died. Patients who were 20 or more years of age had a more severe course than those who were younger. Neurologic events occurred in 11 percent of patients, among whom 46 percent had respiratory failure. Treatment with phenotypically matched transfusions improved oxygenation, with a 1 percent rate of alloimmunization. One fifth of the patients who were treated with bronchodilators had clinical improvement. Eighty-one percent of patients who required mechanical ventilation recovered. A specific cause of the acute chest syndrome was identified in 38 percent of all episodes and 70 percent of episodes with complete data. Among the specific causes were pulmonary fat embolism and 27 different infectious pathogens. Eighteen patients died, and the most common causes of death were pulmonary emboli and infectious bronchopneumonia. Infection was a contributing factor in 56 percent of the deaths.

CONCLUSIONS

Among patients with sickle cell disease, the acute chest syndrome is commonly precipitated by fat embolism and infection, especially community-acquired pneumonia. Among older patients and those with neurologic symptoms, the syndrome often progresses to respiratory failure. Treatment with transfusions and bronchodilators improves oxygenation, and with aggressive treatment, most patients who have respiratory failure recover.

Sickle-cell disease not identified by newborn screening because of prior transfusion

Erythrocyte transfusion can impair detection of sickle-cell disease, galactosemia, or biotinidase deficiency with newborn screening. We report on 4 infants with SCD in whom delayed diagnosis was associated with neonatal transfusion. In 2 cases, the initial newborn screening showed no hemoglobin S. In no case was the recommended screening >/=120 days from the last transfusion obtained. Two children had significant SCD-related morbidity before diagnosis.

Major changes in sickle cell disease

Clinical, molecular, and genetic advances have revealed new pathophysiologic insights and treatments for the growing number of recognized hematologic and nonhematologic abnormalities in sickle cell disease. Treatment targets of cellular dehydration, sickle hemoglobin concentrations, endothelial dysfunction, and abnormal coagulation regulation have been validated as potential therapy. New uses for transfusion therapy hold the promise of decreased major symptoms of acute chest syndrome, stroke, and severe pain crises, but at the expense of increased risk for transfusion reactions, infections, and iron overload. Accumulated experience with autologous, chimeric, and stem cell bone marrow transplantation holds promise for a small percentage of patients with disease. Patient selection, suitable donors, and early mortality are still limiting factors. Genetic manipulation, which offers hope for ameliorating the disease in a larger percentage of patients, is progressing slowly. Combination and staged therapies will be developed and matched to the severity and progression of the patient's disease. Strategies for prevention of major organ damage to the brain, heart, lungs, and kidneys will be prospectively evaluated and refined.

Erythrocytapheresis for chronically transfused children with sickle cell disease: an effective method for maintaining a low hemoglobin S level and reducing iron overload

Cerebrovascular accident (CVA) is a major complication of sickle cell disease during childhood. Long-term transfusion reduces the hemoglobin S level and generally prevents recurrent stroke, but it also results in progressive iron overload that requires regular chelation therapy. Erythrocytapheresis offers an alternative approach aimed at reducing the iron accumulation. We reviewed the results of erythrocytapheresis in eight sickle cell patients (mean age of 12.1 years) at high risk for a first or recurrent stroke. They were maintained at the standard pre-transfusion hemoglobin S (Hb S) level of 30%. Over an average of 9 months of erythrocytapheresis, none of the patients developed complications related to the procedure or to the increased blood use. Ferritin levels decreased by a mean of 26.5% in all patients. When evaluating the ferritin level in five patients, who remained on chelation therapy with deferoxamine (DFO), the level dropped by a mean of 32%. The levels remained stable in the three patients who were not on DFO. The procedure is safe and effective in reducing iron overload and can obviate the need for chelation therapy, even when the target Hb S is maintained at the standard 30% range.

The perioperative complication rate of orthopedic surgery in sickle cell disease: report of the National Sickle Cell Surgery Study Group

Orthopedic disease affects the majority of sickle cell anemia patients of which aseptic necrosis of the hip is the most common, occurring in up to 50% of patients. We conducted a multicentered study to determine the perioperative complications among sickle cell patients assigned to different transfusion regimens prior to orthopedic procedures: 118 patients underwent 138 surgeries. The overall serious complication rate was 67%. The most common of these were excessive intraoperative blood loss, defined as in excess of 10% of blood volume. The next most common complication was sickle cell-related events (acute chest syndrome or vaso-occlusive crisis), which occurred in 17% of cases. While preoperative transfusion group assignment did not predict overall complication rates, higher risk procedures were associated with significantly higher rates of overall complications. Transfusion complications were experienced by 12% of the patients. Two patients died following surgery. Both deaths were associated with an acute pulmonary event. The 52 patients undergoing hip replacements experienced the highest rate of complications with excessive intraoperative blood loss occurring in the majority of patients. Sickle cell-related events occurred in 19% of patients, and surgical complications occurred after 15% of hip replacements and included postoperative hemorrhage, dislocated prosthesis, wound abscess, and rupture of the femoral prosthesis. There were twenty-two hip coring procedures. Acute chest syndrome occurred in 14% of the patients. Overall, decompression coring was a safer, shorter operation. A randomized prospective trial to determine the perioperative and long-term efficacy of core decompression for avascular necrosis of the hip in sickle cell disease is needed. In conclusion, this study demonstrates a high rate of perioperative complications despite compliance with sickle cell perioperative care guidelines. Pulmonary complications and transfusion reactions were common. This study supports the results previously published by the National Preoperative Transfusion in Sickle Cell Disease Group. These results stated that a conservative preoperative transfusion regimen to bring hemoglobin concentration to between 9 and 11 g/dl was as effective as an aggressive transfusion regimen in which the hemoglobin S level was lowered to 30%.

The perioperative complication rate of orthopedic surgery in sickle cell disease: report of the National Sickle Cell Surgery Study Group

Orthopedic disease affects the majority of sickle cell anemia patients of which aseptic necrosis of the hip is the most common, occurring in up to 50% of patients. We conducted a multicentered study to determine the perioperative complications among sickle cell patients assigned to different transfusion regimens prior to orthopedic procedures: 118 patients underwent 138 surgeries. The overall serious complication rate was 67%. The most common of these were excessive intraoperative blood loss, defined as in excess of 10% of blood volume. The next most common complication was sickle cell-related events (acute chest syndrome or vaso-occlusive crisis), which occurred in 17% of cases. While preoperative transfusion group assignment did not predict overall complication rates, higher risk procedures were associated with significantly higher rates of overall complications. Transfusion complications were experienced by 12% of the patients. Two patients died following surgery. Both deaths were associated with an acute pulmonary event. The 52 patients undergoing hip replacements experienced the highest rate of complications with excessive intraoperative blood loss occurring in the majority of patients. Sickle cell-related events occurred in 19% of patients, and surgical complications occurred after 15% of hip replacements and included postoperative hemorrhage, dislocated prosthesis, wound abscess, and rupture of the femoral prosthesis. There were twenty-two hip coring procedures. Acute chest syndrome occurred in 14% of the patients. Overall, decompression coring was a safer, shorter operation. A randomized prospective trial to determine the perioperative and long-term efficacy of core decompression for avascular necrosis of the hip in sickle cell disease is needed. In conclusion, this study demonstrates a high rate of perioperative complications despite compliance with sickle cell perioperative care guidelines. Pulmonary complications and transfusion reactions were common. This study supports the results previously published by the National Preoperative Transfusion in Sickle Cell Disease Group. These results stated that a conservative preoperative transfusion regimen to bring hemoglobin concentration to between 9 and 11 g/dl was as effective as an aggressive transfusion regimen in which the hemoglobin S level was lowered to 30%.

Transfusion practice for patients with sickle cell disease

The practice of transfusion for patients with sickle cell disease is changing. Diminished childhood mortality is resulting in greater patient longevity and a higher prevalence of chronic systemic complications. Many of these chronic complications, as well as several acute ones, are treatable with erythrocyte transfusion. Proactive or preventive uses for transfusion are being considered for selected patients. Immunologic phenomena, hemosiderosis, and risk for transmission of infectious agents are the three most noticeable risks associated with repetitive transfusion. Evolving work with alternative oxygen carriers and surface modification of erythrocytes is also promising and relevant for patients with sickle cell disease.

Silent cerebral infarcts in sickle cell anemia: a risk factor analysis. The Cooperative Study of Sickle Cell Disease

BACKGROUND

Silent infarcts have been reported in 17% of young patients with sickle cell disease and are associated with impaired performance on standardized psychometric tests. Risk factors for the development of these lesions have not been identified.

METHODS

Investigators in the Cooperative Study of Sickle Cell Disease performed a brain magnetic resonance imaging scan on sickle cell anemia patients age 5.9 years and older who had been followed according to the protocols of the Cooperative Study since birth. Individuals with a known history of cerebrovascular accident were excluded from this analysis. Patients with and without silent infarctions were compared with regard to clinical and laboratory parameters.

RESULTS

The study sample included 42 patients (18.3%) with silent infarcts. Patients who had silent infarcts were significantly more likely to have a clinical history of seizure and a lower painful event rate. Lower hemoglobin level, increased leukocyte count, elevated pocked red blood cell count, and SEN betaS globin gene haplotype were associated also with the presence of silent infarcts. There was no relationship between silent infarcts and platelet count, fetal hemoglobin level, reticulocyte percentage, serum aspartate aminotransferase level, total bilirubin concentration, blood pressure, growth parameters, or presence of alpha-thalassemia. A multivariate model for silent infarction identified the following as risk factors: low pain event rate, history of seizure, leukocyte count >/=11.8 x 10(9)/L, and the SEN betaS globin gene haplotype.

CONCLUSIONS

Patients with risk factors for silent infarcts should be evaluated for cerebrovascular disease. If evidence of infarction is found, consideration must be given to therapeutic intervention. At present, the appropriate treatment has not been determined.

Deferoxamine treatment during pregnancy: is it harmful?

The use of the iron chelator, Deferoxamine (DFO), in pregnant thalassemia women with iron overload has been generally avoided due to fear of its potential teratogenicity. We describe a case of a pregnant thalassemia major patient with iron overload, who received DFO throughout her second and third trimesters and gave birth to a healthy infant, who had no findings of DFO toxicity at birth and at a later follow-up. Review of the literature discloses over 40 other cases in which DFO was given in various periods of gestation without evidence of teratogenic effect. Sufficient documentation exists, therefore, to suggest that DFO can be considered for use in cases of pregnant women who need iron chelation treatment.

Sample suitability for the detection of minor white cell populations (microchimerism) by polymerase chain reaction

BACKGROUND

There is increasing use of highly sensitive testing with polymerase chain reaction (PCR) to study white cell microchimerism after transfusion and transplantation. This study investigated possible artifactual sources of allogeneic sample contamination before PCR testing.

STUDY DESIGN AND METHODS

Quantitative Y-chromosome PCR was used to study microchimerism among transfused patients with sickle cell disease (SCD) and thalassemia by using residual specimens from the clinical laboratory. High levels of circulating male white cells among transfused patients with SCD but not thalassemia led to concern over the artifactual origin of male cells. To investigate, paired specimens were collected from 26 female SCD patients: one specimen underwent processing only for PCR, while the other underwent testing in the clinical laboratory before PCR as a process control. All laboratory instruments were also assessed for their ability to impart male allogeneic cells to aliquots of female blood.

RESULTS

Thirty-three (31%) of 107 SCD samples, but 0 of 20 thalassemia samples, gave a high-level PCR signal. One of 26 paired samples that was not exposed to clinical laboratory equipment had low-level PCR positivity while 10 of the 26 became strongly positive after testing on a blood cell analyzer and a reticulocyte analyzer. Sixteen of 32 female samples became positive after reticulocyte analysis, while none became positive after blood cell analysis. Samples from thalassemia patients tested PCR-negative because reticulocyte counts had not been performed.

CONCLUSION

Allogeneic cell contamination is common with clinical laboratory equipment. These samples may not be suitable for microchimerism studies. In addition to method controls, process controls should be employed where appropriate.

The morbidity of bone disease in thalassemia

As thalassemia patients age, bone disease becomes a serious cause of morbidity. The frequency and type of bone disease is affected by the underlying type of thalassemia and its treatment. Problems include rickets, scoliosis, spinal deformities, nerve compression, fractures and severe osteoporosis. In early stages, patients may be asymptomatic but can present with back pain, a limp, dyspnea, neurological emergencies, or sudden fractures. The etiologies are often multifactorial, culminating with increased bone resorption and remodeling. They include hormonal deficiency, bone marrow expansion, nutritional deficiency, or desferal toxicity. Particular risk factors include older patients, low baseline hemoglobin, delayed puberty, hormonal failure, and high iron stores. Nutritional deficiencies may further compound the patient's risk for bone disease. Increasing evidence suggests that these complications and their associated long-term morbidity can be prevented if an annual screening is done, followed by long-term intervention. Patients treated with amino biphosphonates inhibit bone resorption and may demonstrate rapid healing. Intra-nasal calcitonin has also been successful in treating osteopenia. Early use of estrogen and testosterone appears to markedly lower the risk for selective patients. Both transfused and non-transfused patients should be educated about risk factors and early symptoms. All patients should be screened annually for bone disease. Once adolescence occurs, annual testing in selected cases should include bone density studies with X-ray absorptiometry.

The hemoglobin E syndromes

Heterozygotes and homozygotes for HbE (beta 26, GAG-AAG, Glu-Lys) are microcytic, minimally anemic, and asymptomatic. The microcytosis is attributed to the beta thalassemic nature of the beta E gene, whereas the in vitro instability of HbE does not contribute to the phenotype. However, the compound heterozygote state HbE/beta thalassemia results in a variable, and often severe anemia, with the phenotype ranging from transfusion dependence to a complete lack of symptoms. This has been well documented in Thailand, but the basis of the interaction and the cause of the variability remains unexplained. We have studied 50 HbE/beta thalassemics from the UK and 16 from Oakland, CA and assessed the role of HbE instability. Time-course globin chain synthesis experiments have shown that instability is not an important factor in the steady state, but that at 41 degrees C newly synthesized Hb molecules are unstable. We have identified one family in which HbE interacts with pyrimidine 5' nucleotidase deficiency to cause severe anemia with Hb instability. The UK individuals, mostly of Bengali origin, have Hb's from 4.5-11 g/dl. The beta thalassemia mutation, alpha thalassemia and the Xmn 1 G gamma polymorphism do not explain this variability, but the relative and absolute amounts of HbF correlate significantly with total Hb. The Oakland individuals, mostly from Southeast Asia, show similar variation in Hb, which again is largely unexplained.

Correction of the anemia of epidermolysis bullosa with intravenous iron and erythropoietin

Severe forms of epidermolysis bullosa result in a transfusion-dependent chronic anemia and are fatal. The cause of the anemia is unknown. We evaluated five children whose anemia failed to respond to oral iron but who became transfusion independent after treatment with intravenous iron and human recombinant erythropoietin.

New considerations in the treatment of sickle cell disease

The familial pattern of recurring pain and early death seen so often among those affected by sickle cell disease has been long recognized within African cultures, though its first clear description in Western medical literature did not appear until 1910 (1). Although most common in persons of African ancestry, the mutation giving rise to the sickle gene arose independently in several locations where malaria was prevalent (2), traveled with migrating populations, and is now widely distributed among regions and ethnic groups. Recognizing the qualitative abnormality of sickle hemoglobin as a prototype, Pauling & Castle established the notion of a molecular disease (3). Ironically, while the biochemistry and molecular biology of sickle cell disease has been intensively investigated, research into patient care has been limited in scope until recently. Prospective study of large patient groups diagnosed at birth is now providing insight into the disease's natural history and facilitating investigational treatments. Newborn diagnosis, combined with study of new drugs, cytokines, surgical procedures, and a more proactive utilization of transfusion is leading to greatly improved care and survival. Life expectancy is increasing (4) but adults are experiencing more complications of chronic organ dysfunction. A few patients have been cured by stem-cell transplantation, but difficult problems will continue to limit its application.

Hydroxyurea in children with sickle cell disease: impact on splenic function and compliance with therapy

PURPOSE

Hydroxyurea therapy reduces clinical complications in sickle cell disease. While evaluating the clinical and laboratory responses to hydroxyurea in children with sickle cell disease, we concurrently objectively monitored, for the first time during such treatment, compliance with therapy. Because most deaths in affected children are related to infection, we also evaluated the impact of hydroxyurea on splenic function, estimated by the percentage of red cells containing endocytic vacuoles ("pitted" cells) over 1 year of therapy.

PATIENTS AND METHODS

Seventeen children with a history of > or = 3 hospital admissions in the previous year, aged (mean +/- standard error of mean) 12.3 +/- 1.2 years, were treated with hydroxyurea. Clinical and laboratory assessments monitored efficacy and toxicity. Compliance was monitored using computerized pill bottles containing cap microprocessors which monitor the frequency of bottle openings.

RESULTS

Over 18.5 +/- 2.1 months, compliance with hydroxyurea (as determined by percent of the prescribed drug actually taken) was 96 +/- 2%, resulting in increases in mean fetal hemoglobin from 7.7 +/- 1.6% to 16.7 +/- 1.8% (p < 0.005). In 11 patients who reached maximum tolerated doses, an increase to 18.8 +/- 2.5% (p = 0.0001) was observed. Pitted red cell counts did not change. Annual rates of vaso-occlusive crisis (p = 0.0105), acute chest syndrome (p = 0.0417), transfusions administered (p = 0.0168), and days in hospital (p = 0.0017) all decreased significantly.

CONCLUSIONS

Hydroxyurea in children is associated with sustained excellent compliance and monitoring this compliance is uncomplicated. Splenic function in most hydroxyurea-treated children did not change over 1 year of therapy.

Hydroxyurea in children: present and future

Children with sickle cell anemia provide the best opportunity to assess the efficacy of hydroxyurea (HU) in preventing complications and progressive organ damage. The possibility of treating infants with sickle cell disease (SCD) to inhibit the development of organ dysfunction may be the most important future use of HU. The possibility even exists that instituting HU in the neonate may stop the fetal-to-adult globin chain switch and thus markedly change the clinical phenotype of SCD. Recent data suggest HU may also be especially beneficial in children not only by increasing hemoglobin F (HbF), but also by altering the adhesive receptors expressed on red blood cells and vascular endothelium, further increasing the possibility that vasculopathy can be prevented. Six pediatric trials that included small numbers of severely ill patients have been reported recently. All patients received relatively standard HU doses. All studies reported a significant improvement in HbF and mean corpuscular volume and a mild to marked increase in hemoglobin. The clinical response to HU in children with SCD seems to be consistent. The National Institutes of Health pediatric multicenter trial should help answer the question of short-term HU toxicity; however, questions remain concerning long-term risks, such as carcinogenesis, gametogenesis, marrow toxicity, growth retardation, and chromosomal damage. Long-term studies are needed to answer these questions. The future treatment of most children with SCD with HU alone or in combination with other agents looks promising, and long-term trials are warranted.

Cholecystectomy in sickle cell anemia patients: perioperative outcome of 364 cases from the National Preoperative Transfusion Study. Preoperative Transfusion in Sickle Cell Disease Study Group

Cholecystectomy is the most common surgical procedure performed in sickle cell anemia (SCA) patients. We investigated the effects of transfusion and surgical method on perioperative outcome. A total of 364 patients underwent cholecystectomy: group 1 (randomized to aggressive transfusion) 110 patients; group 2 (randomized to conservative transfusion) 120 patients; group 3 (nonrandomized nontransfusion) 37 patients; and group 4 (nonrandomized transfusion) 97 patients. Patients were similar except group 3 patients were more likely to be female, over 20 years old, smokers, and more healthy by American Society of Anesthesiologists (ASA) physical status score. Total complication rate was 39%: sickle cell events 19%; intraoperative or recovery room events 11%; transfusion complications 10%; postoperative surgical events 4%; and death 1%. Group 3 patients had the highest incidence of sickle cell events (32%). Open cholecystectomies were performed in 58% and laparoscopic in 42%. Laparoscopic patients were younger and more healthy by ASA score. Laparoscopic patients had longer anesthesia time (3.2 v 2.9 hours), but shorter hospitalization time (6.4 days v 9.8). Complications were similar between these two groups. We conclude that SCA patients undergoing cholecystectomy have a high perioperative morbidity, and the incidence of sickle cell events may be higher in patients not preoperatively transfused. We recommend a conservative preoperative transfusion regimen, and we encourage the use of the laparoscopic technique for SCA patients undergoing elective cholecystectomy.

Acute chest syndrome in sickle cell disease: clinical presentation and course. Cooperative Study of Sickle Cell Disease

Acute chest syndrome (ACS) is an important cause of morbidity and mortality in sickle cell disease (SCD). Previous studies reported conflicting pictures of ACS making therapeutic interventions difficult. The Cooperative Study of Sickle Cell Disease prospectively followed 3,751 patients enrolled from birth to 66 years of age for ACS. Data on presenting signs and symptoms, laboratory findings, and hospital course were collected. There were 1,722 ACS episodes in 939 patients. Young children (age 2 to 4 years) presented with fever and cough, a negative physical exam, and rarely had pain. Adults were often afebrile and complained of shortness of breath, chills, and severe pain. Upper lobe disease was more common in children; multilobe and lower lobe disease affected adults more often. Severe hypoxia occurred in 18% of adults tested and could not be predicted by examination or laboratory findings. Bacteremia was documented in 3.5% of episodes, but was strongly influenced by age (14% of infants and 1.8% of patients > 10 years). ACS was most common in winter with children having the most striking increase. Transfusion was used less frequently, but earlier in children. Young children were hospitalized for 5.4 days versus 9 days for adults. Fifty percent of adults had a pain event in the 2 weeks preceding ACS and children were more likely to have febrile events. The death rate was four times higher in adults than in children. Fatal cases generally developed rapid pulmonary failure and one third were associated with bacteremia. Age has a striking effect on the clinical picture of ACS. In children, ACS was milder and more likely due to infection, whereas in adults ACS was severe, associated with pain and had a higher mortality rate.

New therapies and approaches to transfusion in sickle cell disease in children

Until recently, transfusion was the only effective therapy for children with sickle cell disease (SCD). Although transfusion can be used to prevent or treat many of the complications of SCD, it has often been used indiscriminantly and with considerable risk to the patient. Recent studies attempted to define those clinical situations in which transfusion is effective as well as to optimize its delivery while minimizing complications. Other therapies are emerging, and in the future many will likely play an important role in the treatment of children with SCD. These therapies include pharmacologic interventions, such as hydroxyurea; bone marrow and cord blood transplantation; and improvements in supportive and preventive care. The future for new therapies looks promising, but the appropriate role for many of these therapeutic interventions remains to be determined.

Core decompression in avascular necrosis of the hip in sickle-cell disease

Sickle-cell disease (SCD) is the most common cause of avascular necrosis (AVN) of the hip in childhood. It results in significant physical impairment and chronic pain, and often progresses to require hip replacement. Conservative therapy is ineffective. We evaluated whether core decompression can arrest progression of AVN. We performed 13 coring procedures in 10 patients with SCD and AVN. Patients ranged from age 9-21 years at diagnosis (mean, median age, 15 years); five hips were stage I, six hips were stage II, and two hips were stage III. Mean follow-up on these patients was 3.7 years. Efficacy of the procedure was evaluated by clinical improvement in pain, radiographic progression, and need for further surgery. All 5 stage I patients had substantial improvement in pain, and only one showed X-ray progression. Five of the 6 (83%) stage II patients had improvement in pain, and 2 patients progressed on X-ray. Both stage III patients progressed on X-ray, but one was clinically improved. None of the 10 patients has required further surgery. Our results demonstrate that in early AVN, core decompression was beneficial for almost all patients, even with progression on X-ray. Core decompression should be considered in the management of SCD patients with early AVN.

Core decompression in avascular necrosis of the hip in sickle-cell disease

Sickle-cell disease (SCD) is the most common cause of avascular necrosis (AVN) of the hip in childhood. It results in significant physical impairment and chronic pain, and often progresses to require hip replacement. Conservative therapy is ineffective. We evaluated whether core decompression can arrest progression of AVN. We performed 13 coring procedures in 10 patients with SCD and AVN. Patients ranged from age 9-21 years at diagnosis (mean, median age, 15 years); five hips were stage I, six hips were stage II, and two hips were stage III. Mean follow-up on these patients was 3.7 years. Efficacy of the procedure was evaluated by clinical improvement in pain, radiographic progression, and need for further surgery. All 5 stage I patients had substantial improvement in pain, and only one showed X-ray progression. Five of the 6 (83%) stage II patients had improvement in pain, and 2 patients progressed on X-ray. Both stage III patients progressed on X-ray, but one was clinically improved. None of the 10 patients has required further surgery. Our results demonstrate that in early AVN, core decompression was beneficial for almost all patients, even with progression on X-ray. Core decompression should be considered in the management of SCD patients with early AVN.

The spectrum of brain MR abnormalities in sickle-cell disease: a report from the Cooperative Study of Sickle Cell Disease

PURPOSE

To define the spectrum of abnormalities in sickle-cell disease, including infarction, atrophy, and hemorrhage, that are identified by brain MR imaging.

METHODS

All MR studies included T1, T2, and intermediate pulse sequences. Images were interpreted without knowledge of the clinical history or neurologic examination findings. Brain MR imaging was performed in 312 children with sickle-cell disease.

RESULTS

Seventy patients (22%) had infarction/ischemia and/or atrophy, infarction/ischemia was noted in 39 children (13%) who had no history of a stroke (the "silent" group). The prevalence rates for silent lesions were 17% for sickle-cell anemia and 3% for hemoglobin sickle-cell disease. For patients with sickle-cell anemia and a history of cerebrovascular accident, infarction/ischemia lesions typically involved both cortex and deep white matter, while silent lesions usually were confined to deep white matter. Within the age range studied, the prevalence of infarction/ischemia did not increase significantly with age, although older patients with lesions had more lesions than did younger patients with lesions.

CONCLUSIONS

Brain MR imaging showed infarction/ischemia in the absence of a recognized cerebrovascular accident in 13% of patients. The prevalence of these lesions did not increase significantly between the ages of 6 and 14 years, suggesting that lesions are present by age 6. However, the increase in the average number of lesions per patient with age may indicate progressive brain injury.

Phospholipase A2 levels in acute chest syndrome of sickle cell disease

Acute chest syndrome (ACS) is associated with significant morbidity and is the leading cause of death in patients with sickle cell disease (SCD). Recent reports suggest that bone marrow fat embolism can be detected in many cases of severe ACS. Secretory phospholipase A2 (sPLA2) is an important inflammatory mediator and liberates free fatty acids, which are felt to be responsible for the acute lung injury of the fat embolism syndrome. We measured SPLA2 levels in 35 SCD patients during 20 admissions for ACS, 10 admissions for vaso-occlusive crisis, and during 12 clinic visits when patients were at the steady state. Eleven non-SCD patients with pneumonia were also evaluated. To determine if there was a relationship between sPLA2 and the severity of ACS we correlated SPLA2 levels with the clinical course of the patient. In comparison with normal controls (mean = 3.1 +/- 1.1 ng/mL), the non-SCD patients with pneumonia (mean = 68.6 +/- 82.9 ng/mL) and all three SCD patient groups had an elevation of SPLA2 (steady state mean = 10.0 +/- 8.4 ng/mL; vaso-occlusive crisis mean = 23.7 +/- 40.5 ng/mL; ACS mean = 336 +/- 209 ng/mL). In patients with ACS sPLA2 levels were 100-fold greater than normal control values, 35 times greater than values in SCD patients at baseline, and five times greater than non-SCD patients with pneumonia. The degree of SPLA2 elevation in ACS correlated with three different measures of clinical severity and, in patients followed sequentially, the rise in SPLA2 coincided with the onset of ACS. The dramatic elevation of SPLA2 in patients with ACS but not in patients with vaso-occlusive crisis or non-SCD patients with pneumonia and the correlation between levels of SPLA2 and clinical severity suggest a role for SPLA2 in the diagnosis and, perhaps, in the pathophysiology of patients with ACS.

Ototoxicity in hemoglobinopathy patients chelated with desferrioxamine

PURPOSE

Ototoxicity often limits the dose of desferrioxamine (DFO) tolerated by patients who are transfusion dependent. Current recommendations advise doses of < 50 mg/kg/day after early reports noted higher rates of oxotoxicity with increasing doses. There have been no follow-up studies to determine the effect of this recommendation on oxotoxicity and iron overload.

METHODS

We followed 28 patients who were chronically chelated with serial audiograms over a 5-year period. Patients with and without oxotoxicity were compared with respect to age, disease, DFO dose, peak DFO dose, length of DFO therapy, ferritin, and therapeutic index.

RESULTS

Eight of the 28 patients (29%) had an abnormal audiogram during threshold testing. Two patients had two separate episodes with hearing deficit. Nine of the 10 episodes were high-frequency losses, with seven being moderate and three mild. All deficits were rapidly reversible with DFO dose reduction. No significant differences were found between the affected and unaffected groups with respect to age, DFO dose or duration, ferritin, or therapeutic index. Numbers of affected patients were small, but patients with SCD differed from patients with thalassemia in that they developed ototoxicity earlier and with lower doses of DFO and lower therapeutic indexes.

CONCLUSIONS

Despite DFO doses usually felt to be low risk for ototoxicity, we found a high rate of ototoxicity in our patients who we've chronically chelated. No variables were identified that reliably predicted ototoxicity. We stress the need for regular audiological exams and feel no dose of DFO is "safe" from the development of ototoxicity.

A comparison of conservative and aggressive transfusion regimens in the perioperative management of sickle cell disease. The Preoperative Transfusion in Sickle Cell Disease Study Group

BACKGROUND

Preoperative transfusions are frequently given to prevent perioperative morbidity in patients with sickle cell anemia. There is no consensus, however, on the best regimen of transfusions for this purpose.

METHODS

We conducted a multicenter study to compare the rates of perioperative complications among patients randomly assigned to receive either an aggressive transfusion regimen designed to decrease the hemoglobin S level to less than 30 percent (group 1) or a conservative regimen designed to increase the hemoglobin level to 10 g per deciliter (group 2).

RESULTS

Patients undergoing a total of 604 operations were randomly assigned to group 1 or group 2. The severity of the disease, compliance with the protocol, and the types of operations were similar in the two groups. The preoperative hemoglobin level was 11 g per deciliter in group 1 and 10.6 g per deciliter in group 2. The preoperative value for hemoglobin S was 31 percent in group 1 and 59 percent in group 2. The most frequent operations were cholecystectomies (232), head and neck surgery (156), and orthopedic surgery (72). With the exception of transfusion-related complications, which occurred in 14 percent of the operations in group 1 and in 7 percent of those in group 2, the frequency of serious complications was similar in the two groups (31 percent in group 1 and 35 percent in group 2). The acute chest syndrome developed in 10 percent of both groups and resulted in two deaths in group 1. A history of pulmonary disease and a higher risk associated with surgery were significant predictors of the acute chest syndrome.

CONCLUSIONS

A conservative transfusion regimen was as effective as an aggressive regimen in preventing perioperative complications in patients with sickle cell anemia, and the conservative approach resulted in only half as many transfusion-associated complications.

Chronic pulmonary disorders in sickle cell disease: findings at thin-section CT

PURPOSE

To characterize the non-acute abnormalities seen at computed tomography (CT) in patients with sickle cell (SC) disease and a prior history of acute chest syndrome (ACS)-pneumonia.

MATERIALS AND METHODS

Twenty-nine patients with SC disease who had experienced one to more than 10 (median, six) previous episodes of ACS-pneumonia were prospectively studied with thin-section CT of the thorax. Scans were graded for interstitial disease and assigned a disease index ranging from 0 to 3. Twenty-four patients underwent pulmonary function tests (PFTs) and measurement of their blood gasses.

RESULTS

Twelve of the 29 patients (41%) had significant interstitial disease that was multifocal. A correlation was found between the disease index and number of episodes of ACS-pneumonia (P = .02) but not between the disease index and PFT results.

CONCLUSION

Thin-section CT demonstrates significant multifocal interstitial lung abnormalities in 41% of selected patients with SC disease. The pattern is most consistent with scarring from episodes of infarction or infection.

A cautionary note regarding hydroxyurea in sickle cell disease

Hydroxyurea can increase fetal hemoglobin (HbF) and improve the clinical course of sickle cell disease (SCD) patients. However, several issues of hydroxyurea therapy remain unresolved, including differences in patients' drug clearance, predictability of drug response, reversibility of sickle cell disease-related organ damage by hydroxyurea, and the efficacy of elevated HbF. We treated two patients with hydroxyurea for periods of 1 to 4 years, monitoring clinical course and laboratory parameters at regular intervals. The first patient (patient A) had a history of chronic pain and extensive hospitalizations. The second patient (patient B) had a history of stroke and refused to continue with chronic transfusion therapy and chelation. Both patients showed a fivefold to tenfold increase in HbF (5% to 25%, 3% to 31%). However, patient A developed an acute chest syndrome, despite an HbF level of 20%. After red blood cell transfusions for hypoxia, the HbF level decreased to 5%. When hydroxyurea dosage was increased, pancytopenia developed and was not resolved until 2 months after hydroxyurea was discontinued; Patient B developed a cerebral hemorrhage on hydroxyurea; he died shortly thereafter. His HbF level was 21% before death. We noted an increase in HbF and a general improvement in the two patients. However, both experienced major SCD-related complications despite HbF levels over 20%. Our findings also suggest that the progressive vascular changes associated with SCD are unlikely to be dramatically affected by increased HbF levels. Because neither the efficacy nor the toxicity of hydroxyurea have been thoroughly investigated, physicians should be cautious in prescribing hydroxyurea for patients with SCD before completion of the National Clinical Trial.

Butyrate derivatives. New agents for stimulating fetal globin production in the beta-globin disorders

PURPOSE

Stimulating expression of the normal fetal globin genes is a preferred method of ameliorating sickle cell disease and beta-thalassemia for the majority of patients in North America who do not have appropriate bone marrow donors.

PATIENTS AND METHODS

Due to increased survival of red blood cells that contain both hemoglobin S and hemoglobin F, as little as 4-8% fetal globin synthesis in the bone marrow can produce levels of hemoglobin F of approximately 20% in the peripheral circulation. Some success has been achieved in stimulating hemoglobin F using chemotherapeutic agents (such as hydroxyurea and 5-azacytidine) and growth factors (erythropoietin) that alter erythroid growth kinetics. However, there is reluctance to treat children with chemotherapeutic agents because of possible undesirable long-term side effects.

RESULTS

Butyric acid and butyrate derivatives are generally safe compounds that stimulate the promoters of individual fetal and embryonic globin genes and thus provide a more specific therapy. An initial trial with the parent compound, given as arginine butyrate, has demonstrated rapid stimulation of fetal globin expression to levels that can ameliorate these conditions. Phase I trials of an oral butyrate derivative with a long plasma half-life have begun.

CONCLUSIONS

These agents may provide a new and specific approach for ameliorating the clinical manifestations of sickle cell disease and beta-thalassemia.